The use of invertase to invert sucrose to fructose and glucose is a known reaction. See, for example, U.S. Pat. No. 1,465,459 wherein the inversion of sugar syrup is disclosed and U.S. Pat. No. 1,534,166 where invertase is used to prevent crystallization of beet molasses solution. Similarly the isomerization of glucose to fructose by an isomerase is known. See for example U.S. Pat. No. 3,689,362. Also, dates have been treated with invertase to inhibit sucrose crystallization, J. Sci. Food Agr., 1975, 26(10), 1523-28.
Fructose has previously been used as a sweetening agent for frozen desserts as disclosed in U.S. Pat. No. 3,236,658 and the use of invertase to make liquid center chocolate candies is also known. In the latter process, disclosed in U.S. Pat. No. 1,437,816, fruit pieces are enrobed with a sugar fondant in a mold form and allowed to cool and solidify. The fondant is then enrobed with chocolate. The fondant is prepared with invertase added which slowly hydrolyzes the sucrose to invert sugar during the normal storage of the candy. The invert sugar is more soluble than sucrose in the moisture of the fondant and thus becomes a liquid. Also, U.S. Pat. No. 4,154,863 at Col. 29 line 50 to Col. 30 line 25 discloses an orange juice concentrate made from ingredients including fructose-dextrose syrup.